Dude, What if This is All, Like, An Illusion?

by on August 15, 2007 · 6 comments

I normally love John Tierney’s work, but boy is this silly. “Man, what if, like, we’re not real, man. What if we’re just a computer simulation like on the Matrix?” Beyond the dorm-room-bull-session character of the whole premise, the argument doesn’t make any sense:

Dr. Bostrom assumes that technological advances could produce a computer with more processing power than all the brains in the world, and that advanced humans, or “posthumans,” could run “ancestor simulations” of their evolutionary history by creating virtual worlds inhabited by virtual people with fully developed virtual nervous systems.

Some computer experts have projected, based on trends in processing power, that we will have such a computer by the middle of this century, but it doesn’t matter for Dr. Bostrom’s argument whether it takes 50 years or 5 million years. If civilization survived long enough to reach that stage, and if the posthumans were to run lots of simulations for research purposes or entertainment, then the number of virtual ancestors they created would be vastly greater than the number of real ancestors.

It might be true that at some point we’ll have the computing power to run precise, molecule-by-molecule simulations of the human brain. But that doesn’t really get you where Bostrom wants to take us. What he wants is a molecule-by-molecule simulation of the entire universe, or at the very least of the entire surface of Planet Earth. Human brains don’t exist in isolation. Their development is intimately shaped by their interaction with the real world. To develop a realistic simulation of the brain, you need a realistic simulation of the world the brain interacts with.

And accurately simulating any given system requires a computer system at least as complex as the system being simulated. We’re only able to simulate things like the weather and car crashes because we make assumptions that radically simplify our models. But that, of course, makes the details of their predictions wrong, especially over long time frames. That’s why weather predictions further out than 10 days are worthless. If you’re trying to simulate a long-term process like the evolution of human society, such radical simplifications wouldn’t be acceptable. If virtual Milikan performs his oil-drop experiment, the simulation had better be detailed enough to keep track of individual electrons, or the physicists of your virtual world will be very confused, and the “science” of our virtual world will evolve in a very different direction.

So an accurate simulation of the world would have to be roughly as complex as the world itself. And since any given computer will presumably only be a small part of the world, the maximum complexity of the worlds it can simulate will necessarily be far simpler than the real world the computer occupies. So while I suppose it’s possible we’re being simulated by a computer in a mind-bogglingly more complex universe, the more plausible explanation is that we’re in the “real” world, whatever that means.

Did the New York Times really just print that?

Update: Tom Lee had almost exactly the same reaction. Although he’s obviously cooler than me, as his college students had a dime bag in addition to their copy of The Matrix.

  • http://kingsley2.com Kingsley

    You don’t need a molecule by molecule simulation. It only needs to meet human perceptual resolution, which is much more achievable than the level you’re talking about.

    In the end, I just think it’s more fun to pretend it’s all real, whatever that means, especially since I doubt if anything can be done about it otherwise.

  • http://kingsley2.com Kingsley

    You don’t need a molecule by molecule simulation. It only needs to meet human perceptual resolution, which is much more achievable than the level you’re talking about.

    In the end, I just think it’s more fun to pretend it’s all real, whatever that means, especially since I doubt if anything can be done about it otherwise.

  • http://www.techliberation.com/ Tim Lee

    It has to meet the perceptual resolution of humans assisted with technology. That is, when one of your simulated humans looks into a microscope or MRI or builds a microchip or a particle accelerator, the simulation should behave in a reasonable manner. I don’t see how you could get all those details right without resorting to particle-by-particle simulation.

  • http://www.techliberation.com/ Tim Lee

    It has to meet the perceptual resolution of humans assisted with technology. That is, when one of your simulated humans looks into a microscope or MRI or builds a microchip or a particle accelerator, the simulation should behave in a reasonable manner. I don’t see how you could get all those details right without resorting to particle-by-particle simulation.

  • LarsG

    The thing is people don’t perceive everything all the time. You might get away with a perception-tracer that works on the same principle as a ray-tracer or 3D renderer. You don’t have to emulate the quantum state of every atom in a microchip as long as the output is correct. It would be tricky to get right; but hey, we’re talking about someone that’s supposed to be capable of building a world-emulating computer.

    The computational requirements would still be enormous. Not in 50 years, we’re likely talking on the scale of a Matrioshka-brain.

    My problem with this gedankenexperiment is that it smells too much of human narcissism. In earlier times, we believed (ok, some still do) that a God created the universe for our benefit, that the sun revolved around the earth, etc. To think that trans-humans would undertake the effort to convert an entire solar system to a computer just to emulate us seems like a modern equivalent of the same line of thought. Me thinks Dr. Bostrom needs to be subjected to the Total Perspective Vortex.

  • LarsG

    The thing is people don’t perceive everything all the time. You might get away with a perception-tracer that works on the same principle as a ray-tracer or 3D renderer. You don’t have to emulate the quantum state of every atom in a microchip as long as the output is correct. It would be tricky to get right; but hey, we’re talking about someone that’s supposed to be capable of building a world-emulating computer.

    The computational requirements would still be enormous. Not in 50 years, we’re likely talking on the scale of a Matrioshka-brain.

    My problem with this gedankenexperiment is that it smells too much of human narcissism. In earlier times, we believed (ok, some still do) that a God created the universe for our benefit, that the sun revolved around the earth, etc. To think that trans-humans would undertake the effort to convert an entire solar system to a computer just to emulate us seems like a modern equivalent of the same line of thought. Me thinks Dr. Bostrom needs to be subjected to the Total Perspective Vortex.

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